A signature is a single section in a book with a sewnbinding, either hardcover or paperback. It is a single piece of paper that may or may not have printing on it, folded and then trimmed at the edges, and sewn together, with other signatures, form the book block. A signature is generally 8, 16, or 32 pages, though it can be more or less.

One may identify a book with a sewn binding by noting that it is comprised of separate signatures, sewn together at the spine, rather than a mass of pages, glued together, and by the stitching between the center two pages of the signature, at the fold.

In most of the booksprinted before the 20th c., and some printed more recently, one can identify the first page of the signature by a letter at the bottom center of the first page of the signature. The signatures are lettered in chronological order, starting with A and going to Z, then from AA to ZZ, etc. This was done so that the bookbinder
would know the proper order to sew the signatures together in.

A resemblance between the external characters of a disease and those of some physical agent, for instance, that existing between the red skin of scarlet fever and a red cloth; -- supposed to indicate this agent in the treatment of the disease.

The designation of the key (when not C major, or its relative, A minor) by means of one or more sharps or flats at the beginning of the staff, immediately after the clef, affecting all notes of the same letter throughout the piece or movement. Each minor key has the same signature as its relative major.

6. Print. (a)

A letter or figure placed at the bottom of the first page of each sheet of a book or pamphlet, as a direction to the binder in arranging and folding the sheets.

(b)

The printed sheet so marked, or the form from which it is printed; as, to reprint one or more signatures.

⇒ Star signatures (as A*, 1*) are the same characters, with the addition of asterisks, used on the first pages of offcuts, as in 12mo sheets.

7. Pharm.

That part of a prescription which contains the directions to the patient. It is usually prefaced by S or Sig. (an abbreviation for the Latin signa, imperative of signare to sign or mark).